The amazing world of the simplest organisms consisting of only one cage is attentively studied by biologists. Processes which happen in monocelled beings are not so simple as can seem. The concept about the building and activity of protozoa helps to struggle with a serious illness at the person. Some protozoa are parasites, they can do harm to people. Other monocelled show surprising similarity of animals and plants.
In all variety of the nature the type of the simplest animals wonderfully is allocated. Parasites who can live in others organism or free living individuals occur among them. They are united by one common feature – the organism of protozoa consists of only one cage.
Monocelled parasites
Examples of the parasitizing monocelled animals are the dysenteric amoeba and a malarial parasite. The dysenteric amoeba differs from an ordinary individual in the short lozhnonozhka. With dirty water it can get to an organism. Destroying intestines, eating its parts and blood, it causes the hardest disease – amoebic dysentery.
The malarial parasite is especially dangerous. Its distribution is promoted by malarial mosquitoes. Getting into a human body, he destroys blood cells and emits toxic substances. It leads to fever of a certain type. Each 2 – 3 days the person has a temperature increase up to 41 °C. Externally, the malarial parasite is similar to an amoeba.
Amoeba ordinary (kornenozhka class)
The colored monocelled being lives at the bottom of reservoirs. For the activity the amoeba chooses the polluted muddy twigs. It can find livelihood in such conditions. The little body of an amoeba can be seen with the naked eye. It represents the small, constantly changing the form lump. But to make out the structure of this colourless being, it is necessary to use a microscope.
In spite of the fact that the amoeba only one cage, it has an independent organism. For movement and search of food to an amoeba serves lozhnonozhka. They are formed by cytoplasm which filled a cage. Except cytoplasm the cage contains a small kernel. The simplest organisms which have lozhnonozhka belong to the class kornenozhek.
For food the amoeba uses plants, bacteria or eats other monocelled. Covering cytoplasm production, it begins to emit digestive juice. The food concluded in digestive vacuoles, formed by cytoplasm, is dissolved and gets in a cage. The remains which were not dissolved under the influence of juice are thrown out of a body outside.
Breath of an amoeba is carried out through cytoplasm. To remove carbon dioxide and other toxic substances from a cage, in an amoeba it is formed special sokratitelny vacuoles. As constantly flows liquid into a little body, it dissolves substances unnecessary an amoeba and fills vacuoles. When there occurs overflow of a bubble of a vacuole, it is cleaned.
Reproduction of an amoeba happens directly by cell division. The kernel begins to be extended, and then breaks into two parts. The banner which is formed on a little body divides it in half, there is a rupture of a cage, and process of division comes to the end. Sokratitelny vacuoles remains in one of amoebas. The second amoeba forms it independently.
At approach of adverse conditions, the amoeba can form a cyst. In it the cage can worry winter or drying of a reservoir. As soon as conditions for life return to normal, the amoeba leaves a cyst and continues the activity.
Paramecium caudatum (infusorian class)
The simplest organism which in a form reminds a shoe lives in muddy and dirty reservoirs. The paramecium caudatum is capable to move quickly at the expense of special zhgutik (eyelashes) which covered its little body. By means of the wavy movements of eyelashes the shoe dexterously moves under water.
Food of a paramecium caudatum is carried out through an oral opening which to be on the middle of a little body. The infusorian eats bacteria. Eyelashes adjust water with food to an opening, and food gets through a mouth directly into a throat. Having passed through a throat of a bacterium, get to cytoplasm, and around them it is formed special digestive vacuoles. Then vacuoles it is disconnected from a throat and goes down stream of cytoplasm which is in the constant movement. Further process of digestion of food at a shoe happens just as at an amoeba. The remains of food are evacuated through a special opening – a poroshitsa.
Process of breath and clarification of an infusorian from toxic substances is carried out by means of two sokratitelny by a vacuole by an example of an amoeba. From all cytoplasm toxic waste products gather and on two bringing tubules get to vacuoles.
One of the kernels located in a cage is responsible for reproduction of a paramecium caudatum. The large kernel is responsible for digestion, movement and allocation. The small kernel is engaged in reproduction. The shoe, as well as an amoeba, breeds cell division.
For this process of a kernel depart from each other. The small kernel begins to be divided into two parts, dispersing by the ends of a little body. After that there is a division of a large kernel. During cell division the shoe stops food, and its little body in the middle forms a banner. The divided kernels disperse by the opposite ends of a body and a half of a cage break up. Two new paramecium caudata are as a result formed.
Green euglena (class flagellates)
Activity of an euglena proceeds in still water, for example, in dirty puddles and twigs with the decaying remains of plants. The extended little body makes in length about 0.05 mm. The euglena has an outer layer of cytoplasm which forms an outer sheath.
For movement she uses special zhgutik which is located on the front end of a little body. Being screwed in zhgutiky in water, she floats forward. This zhgutik gave the name to a class. Biologists consider that flagellates were primogenitors of all protozoa.
The name green, the euglena received thanks to availability of chlorolayers which contain a chlorophyll. Cell nutrition happens due to photosynthesis therefore the euglena prefers to eat on light. It has a special peephole, red color, he is capable to feel light. Therefore the euglena is capable to find the lightest part of a reservoir. If it long time is in the dark, the chlorophyll will disappear, and food will be carried out due to digestion of the organic matter dissolved in water.
The euglena eats two ways. The metabolism depends on the chosen way of food. If it is surrounded by darkness, then exchange proceeds as at an amoeba. If the euglena to be on light, then exchange will be similar to what occurs at plants. Thus, the green euglena proves relationship between the kingdom of plants and fauna. The secretory system and breath at an euglena work also as for an amoeba.
Reproduction of an euglena happens due to cell division. Closer to a back part it located a kernel which is surrounded by cytoplasm. Originally the kernel is divided into two parts, then at an euglena the second is formed zhgutik. Between these zhgutika there is a crack which gradually divides a cage along a little body.
Also as well as the amoeba, an euglena is capable to wait adverse conditions being in a cyst. At it disappears zhgutik, the little body gains rounded shape and becomes covered by a protective cover. In such look the green euglena can worry winter or drying of a reservoir.
Volvox
This unusual animal forms the whole colony of the simplest flagellates. The size of one colony is equal to 1 mm. About 1000 cages are its part. Everything together they form a ball which floats in water.
The structure of a separate cage of colony is similar to the structure of an euglena, except for quantity of zhgutik and a form. The separate cage has the pear-shaped form and is equipped with two zhgutika. The basis of colony is formed by special semi-fluid substance in which zhgutikama cages outside are shipped.
Wonderfully the ball looks a uniform organism which actually consists of independent cages. Coherence of work of zhgutik is based on cytoplasmatic bridges which connect separate cages. The volvox cell division breeds. It occurs in colony. When the new ball is formed, it leaves parent colony.